Geared actuation mechanism and surgical clip applier including the same

ABSTRACT

An actuation mechanism, and a handle assembly and a surgical clip applier including the same are disclosed. The actuation mechanism includes a drive bar movable through a stroke having first and second stroke portions and an output gear rack. First and second intermediate gears include input portions operably coupled to a trigger and output portions defining different diameters. In the first stroke portion, the output portion of the first intermediate gear is engaged with the gear rack such that the first intermediate gear drives the drive bar. In the second stroke portion, the output portion of the second intermediate gear is disposed in engagement with the gear rack such that the second intermediate gear drives the drive bar. A different mechanical advantage is provided in the first portion of the stroke length as compared to the second portion of the stroke length.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. ProvisionalPatent Application No. 62/542,335 filed Aug. 8, 2017, the entiredisclosure of which is incorporated by reference herein.

BACKGROUND Technical Field

The present disclosure relates to surgical clip appliers. Moreparticularly, the present disclosure relates to geared actuationmechanisms for surgical clip appliers and surgical clip appliersincluding the same.

Description of Related Art

Surgical clip appliers are known in the art and are used for a number ofdistinct and useful surgical procedures. In the case of a laparoscopicsurgical procedure, access to the interior of an abdomen is achievedthrough narrow tubes or cannulas inserted through a small entranceincision in the skin. Minimally invasive procedures performed elsewherein the body are often generally referred to as endoscopic procedures.

Endoscopic surgical clip appliers having various sizes (e.g.,diameters), that are configured to apply a variety of diverse surgicalclips, are also known in the art, and are capable of applying a singleor multiple surgical clips during an entry to the body cavity. Suchsurgical clips are typically fabricated from a biocompatible materialand are usually compressed over tissue. Once applied to tissue, thecompressed surgical clip terminates the flow of fluid therethrough.

SUMMARY

As detailed herein and shown in the drawing figures, as is traditionalwhen referring to relative positioning on a surgical instrument, theterm “proximal” refers to the end of the apparatus or component thereofwhich is closer to the user and the term “distal” refers to the end ofthe apparatus or component thereof which is further away from the user.Further, to the extent consistent, any or all of the aspects andfeatures detailed herein may be used in conjunction with any or all ofthe other aspects and features detailed herein.

Provided in accordance with an aspect of the present disclosure is anactuation mechanism for a surgical clip applier including a drive barmovable through a stroke having a first stroke portion and a secondstroke portion to fire at least one surgical clip. The drive barincludes an output gear rack associated therewith. A trigger ispivotable from an un-actuated position to an actuated position. A firstintermediate gear includes an input portion and an output portion. Theinput portion of the first intermediate gear is operably coupled to thetrigger such that pivoting of the trigger from the un-actuated positionto the actuated position rotates the first intermediate gear. A secondintermediate gear includes an input portion and an output portion. Theoutput portions of the first and second intermediate gears definedifferent diameters. The input portion of the second intermediate gearis operably coupled to the trigger such that pivoting of the triggerfrom the un-actuated position to the actuated position rotates thesecond intermediate gear. In the first portion of the stroke length, theoutput portion of the first intermediate gear is disposed in meshedengagement with the gear rack and the output portion of the secondintermediate gear is disengaged from the gear rack such that the firstintermediate gear drives the drive bar along the first portion of thestroke length in response to pivoting of the trigger. In the secondportion of the stroke length, the output portion of the secondintermediate gear is disposed in meshed engagement with the gear rackand the output portion of the first intermediate gear is disengaged fromthe gear rack such that the second intermediate gear drives the drivebar along the second portion of the stroke length in response topivoting of the trigger. A different mechanical advantage is provided inthe first portion of the stroke length as compared to the second portionof the stroke length.

In an aspect of the present disclosure, the mechanical advantageprovided in the first portion of the stroke length is less than themechanical advantage provided in the second portion of the strokelength.

In another aspect of the present disclosure, the first portion of thestroke length is greater than the second portion of the stroke length.

In yet another aspect of the present disclosure, the trigger ispivotable through an input rotation from the un-actuated position to theactuated position. The input rotation includes a first portioncorresponding to the first portion of the stroke length and a secondportion corresponding to the second portion of the stroke length. Insuch aspects, the first portion of the input rotation may be less thanthe second portion of the input rotation and/or the first portion of thestroke length may be greater than the second portion of the strokelength.

In still another aspect of the present disclosure, an input gear isassociated with the trigger and a transmission gear including an inputportion and an output portion is disposed between the input gear and thefirst and second intermediate gears. The input portion of thetransmission gear is disposed in meshed engagement with the input gearand the output portion of the transmission gear disposed in meshedengagement with the input portions of the first and second intermediategears.

A handle assembly of a surgical clip applier provided in accordance withaspects of the present disclosure includes a housing defining a bodyportion and a fixed handle portion extending from the body portion andan actuation mechanism such as the actuation mechanism according to anyof the above-noted aspects or any of the other aspects detailed herein.

In aspects, the housing is configured to receive an elongated assemblysupporting an end effector assembly at a distal end portion thereof. Thedrive bar is configured to operably interface with an actuation memberof the elongated assembly.

A surgical clip applier provided in accordance with aspects of thepresent disclosure includes a handle assembly and an elongated assemblyextending distally from the handle assembly and supporting an endeffector assembly at a distal end portion thereof. The elongatedassembly includes an actuation member movable to fire at least onesurgical clip from the end effector assembly. The handle assemblyincludes a housing defining a body portion and a fixed handle portionextending from the body portion. The handle assembly further includes anactuation mechanism such as the actuation mechanism according to any ofthe above-noted aspects or any of the other aspects detailed herein.

In aspects, the elongated assembly is releasably engagable with thehandle assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects and features of the presently-disclosed geared actuationmechanisms for surgical clip appliers and clip surgical clip appliersincluding the same are described in detail with reference to the drawingfigures wherein like reference numerals identify similar or identicalstructural elements and:

FIG. 1 is a front, perspective view of a surgical clip applier providedin accordance with the present disclosure including a handle assemblyhaving an elongated assembly engaged therewith;

FIG. 2 is front, perspective view of the surgical clip applier of FIG. 1with the elongated assembly removed from the handle assembly;

FIG. 3 is a side, perspective view of a distal end portion of theelongated assembly of FIGS. 1 and 2;

FIG. 4 is a side, perspective view of a distal end portion of anotherelongated assembly configured for use with the surgical clip applier ofFIG. 1;

FIG. 5 is an enlarged, longitudinal, cross-sectional view of a portionof the handle assembly of the surgical clip applier of FIG. 1; and

FIG. 6 is an exploded, side view of an actuation mechanism of the handleassembly of the surgical clip applier of FIG. 1.

DETAILED DESCRIPTION

The present disclosure provides geared actuation mechanisms for surgicalclip appliers and surgical clip appliers including the same.

Turning to FIGS. 1-2, a surgical clip applier embodying the aspects andfeatures of the present disclosure is shown generally identified byreference numeral 10. Surgical clip applier 10 generally includes ahandle assembly 100 and a plurality of elongated assemblies 200, 300(FIG. 4) selectively connectable to handle assembly 100. Handle assembly100 is configured to operate each of the plurality of elongatedassemblies 200, 300 (FIG. 4) upon connection thereto, and may beconfigured as a sterilizable, reusable component such that handleassembly 100 may be repeatedly used with different and/or additionalelongated assemblies 200, 300 (FIG. 4) during the course of one or moresurgical procedures. The elongated assemblies 200, 300 (FIG. 4) may beconfigured as single-use disposable components, limited-use disposablecomponents, or reusable components, depending upon a particular purposeand/or the configuration of the particular elongated assembly. In eitherconfiguration, the need for multiple handle assemblies 100 is obviatedand, instead, the surgeon need only select an appropriate elongatedassembly 200, 300 (FIG. 4) and connect that elongated assembly to handleassembly 100 in preparation for use.

Handle assembly 100 generally includes a housing 110, an actuationmechanism 120 operably associated with housing 110, a latch assembly 160operably associated with housing 110, a rotating receiver assembly 180operably coupled to a distal portion of housing 110, and, inembodiments, a ratchet mechanism (not shown) operably disposed withinhousing 110. Housing 110 supports and/or encloses the operatingcomponents of handle assembly 100 and is detailed below. Actuationmechanism 120 is configured to enable selective firing of one or moresurgical clips (not shown) from the end effector of the attachedelongated assembly, as also detailed below.

Latch assembly 160 is configured to facilitate releasable lockingengagement of the elongated assembly with handle assembly 100. Rotatingreceiver assembly 180 is configured to receive a proximal end portion ofthe elongated assembly and to enable selective rotation thereof relativeto housing 110. The ratchet mechanism is configured to enable ratchetingactuation of actuation mechanism 120, when an elongated assemblyconfigured for ratcheting actuation is connected to handle assembly 100.Details of latch assembly 160, rotating receiver assembly 180, and theratchet mechanism can be found in International Application No.PCT/CN2016/096666, filed on Aug. 26, 2016, the entire contents of whichis hereby incorporated herein by reference. Alternatively oradditionally, latch assembly 160, rotating receiver assembly 180, and/orthe ratchet mechanism may be configured as detailed in InternationalApplication No. PCT/CN2016/071178, filed on Jan. 18, 2016, the entirecontents of which is also hereby incorporated herein by reference.

With additional reference to FIGS. 3 and 4, as noted above, handleassembly 100 is configured for use with different elongated assembliessuch as, for example, elongated assembly 200 (FIGS. 1-3) and elongatedassembly 300 (FIG. 4). Handle assembly 100, more specifically, isconfigured for both ratcheting use, e.g., in connection with elongatedassembly 200 (FIGS. 1-3), and non-ratcheting use, e.g., in connectionwith elongated assembly 300 (FIG. 4). Elongated assemblies 200, 300 aredescribed briefly below. A more detailed discussion of elongatedassemblies, e.g., elongated assemblies 200, 300, configured for use withhandle assembly 100 can be found in International Application Nos.PCT/CN2016/096666 and/or PCT/CN2016/071178, previously incorporated byreference herein in their entireties, and additionally or alternativelyas in International Application No. PCT/CN2015/091603, filed on Oct. 10,2015, the entire contents of which is likewise hereby incorporatedherein by reference.

Referring to FIGS. 1-3, elongated assembly 200 is configured forratcheting use and generally includes a proximal hub 220, an elongatedshaft 240 extending distally from proximal hub 220, an end effectorassembly 260 disposed towards a distal end portion of elongated shaft240, and an inner drive assembly (not shown) operably coupled betweenhandle assembly 100 and end effector assembly 260 when elongatedassembly 200 is engaged with handle assembly 100 to enable thesequential firing of at least one surgical clip (not shown) abouttissue. End effector assembly 260 of elongated assembly 200 may beconfigured to fire surgical clips similar to those shown and describedin U.S. Pat. No. 7,819,886 or 7,905,890, the entire contents of each ofwhich is hereby incorporated herein by reference.

Referring to FIG. 4, elongated assembly 300 is configured fornon-ratcheting use and generally includes a proximal hub (not shown), anelongated shaft 340 extending distally from the proximal hub, an endeffector assembly 360 disposed towards a distal end portion of elongatedshaft 340, and an inner drive assembly (not shown) operably coupledbetween handle assembly 100 and end effector assembly 360 when elongatedassembly 300 is engaged with handle assembly 100 to enable graspingand/or manipulation of tissue, retrieval of a surgical clip, and firingof the surgical clip about tissue. It is contemplated that end effectorassembly 360 of elongated assembly 300 may be configured to firesurgical clips similar to those shown and described in U.S. Pat. No.4,834,096, the entire contents of which is hereby incorporated herein byreference.

Referring generally to FIGS. 1-4, although exemplary elongatedassemblies 200, 300 configured for ratcheting and non-ratcheting use,respectively, are detailed above, it is contemplated that various otherelongated assemblies for performing various different surgical tasksand/or having various different configurations suitable for ratchetingor non-ratcheting use may likewise be utilized with handle assembly 100.

Turning to FIGS. 1, 2, and 5, housing 110 of handle assembly 100 definesa body portion 111 and a fixed handle portion 112 depending from bodyportion 111. Body portion 111 of housing 110 includes an internal pivotpost 114 extending transversely within body portion 111, a retentionpost 116 disposed towards a proximal end of body portion 111 andlikewise extending transversely within body portion 111, and a distalopening 118 through which a proximal end portion of an actuation member“A” of an elongated assembly, e.g., elongated assembly 200 (FIGS. 1-3)or elongated assembly 300 (FIG. 4), extends when the elongated assemblyis engaged with handle assembly 100.

Actuation mechanism 120 is operably supported by housing 110 andincludes a trigger 122, a drive bar 130, a biasing member 140, and agear assembly 150. Trigger 122 includes a grasping portion 123, anintermediate pivot portion 124, and a proximal extension 125. Graspingportion 123 of trigger 122 extends downwardly from body portion 111 ofhousing 110 in opposed relation relative to fixed handle portion 112 ofhousing 110. Grasping portion 123 is configured to facilitate graspingand manipulation of trigger 122. Intermediate pivot portion 124 oftrigger 122 is at least partially disposed within housing 110 anddefines a pivot aperture 126 that is configured to receive pivot post114 of housing 110 so as to enable pivoting of trigger 122 about pivotpost 114 and relative to housing 110, e.g., between an un-actuatedposition, wherein grasping portion 123 of trigger 122 is spaced-apartrelative to fixed handle portion 112, and an actuated position, whereingrasping portion 123 of trigger 122 is approximated relative to fixedhandle portion 112.

Proximal extension 125 of trigger 122 is disposed on an opposite side ofintermediate pivot portion 124 and, thus, pivot post 114, as compared tograsping portion 123 of trigger 122. As such, pivoting of graspingportion 123 to rotate in one direction, e.g., proximally towards fixedhandle portion 112, pivots proximal extension 125 to rotate in theopposite direction, e.g., distally. Proximal extension 125 of trigger122 defines an arcuate gear portion 128 that functions as an input gear152 of gear assembly 150, as detailed below.

The actuation member “A” of the elongated assembly engaged with handleassembly 100 is selectively translatable in response to actuation ofactuation mechanism 120 to fire a surgical clip (not shown) supported atthe end effector assembly of the elongated assembly about tissue. Morespecifically, drive bar 130 is slidably disposed within body portion 111of housing 110 in longitudinal alignment with the actuation member “A”such that distal sliding of drive bar 130 through body portion 111 ofhousing urges a distal end portion 132 of drive bar 130 into contactwith actuation member “A” to thereby translate actuation member “A”distally, e.g., to fire a surgical clip supported at the end effectorassembly of the elongated assembly.

With additional reference to FIG. 6, drive bar 130 defines a linear gearrack 134 extending along at least a portion of an underside surfacethereof. Linear gear rack 134 functions as an output gear 160 of gearassembly 150, as detailed below. Drive bar 130, as detailed above, isslidable through body portion 111 of housing to urge distal end portion132 of drive bar 130 into actuation member “A” to translate actuationmember “A” distally to thereby to fire a surgical clip supported at theend effector assembly of the elongated assembly. Drive bar 130, morespecifically, is slidable from an un-actuated, proximal position to anactuated, distal position in order to fire a surgical clip supported atthe end effector assembly of the elongated assembly. Biasing member 140is engaged at a first, proximal end portion thereof to retention post116 of body portion 111 of housing 110 and at a second, distal endportion thereof through an aperture 136 defined through a proximal endportion 138 of drive bar 130. In this manner, biasing member 140 biasesdrive bar 130 towards the un-actuated, proximal position.

Gear assembly 150 includes, as noted above, an input gear 152 (definedby arcuate gear portion 128 of proximal extension 125 of trigger 122)and an output gear 160 (defined by linear gear rack 134 of drive bar130). Gear assembly 150 further includes a transmission gear 154, afirst intermediate gear 156, and a second intermediate gear 158.

Transmission gear 154 is configured as a compound gear including anarcuate input gear portion 155 a (extending a partial or fullcircumference) and an arcuate output gear portion 155 b (extending apartial or full circumference). Arcuate input gear portion 155 a oftransmission gear 154 is disposed in meshed engagement with input gear152, e.g., arcuate gear portion 128 of proximal extension 125 of trigger122. Transmission gear 154 is rotatably mounted about a pin 155 c thatis fixed relative to and extends transversely through body portion 111of housing 110. In embodiments, arcuate input gear portion 155 a definesan arc having a diameter different from a diameter of the arc defined byarcuate output gear portion 155 b. In embodiments, the diameter ofarcuate input gear portion 155 a is smaller than the diameter of arcuateoutput gear portion 155 b, although other configurations are alsocontemplated.

First and second intermediate gears 156, 158, respectively, similar totransmission gear 154, are configured as compound gears each including arespective arcuate input gear portion 157 a, 159 a (extending a partialor full circumference) and a respective arcuate output gear portion 157b, 159 b (extending a partial or full circumference). Arcuate input gearportions 157 a, 159 a of first and second intermediate gears 156, 158,respectively, are disposed in meshed engagement with arcuate output gearportion 155 b of transmission gear 154. More specifically, firstintermediate gear 156 is positioned proximally adjacent transmissiongear 154 such that arcuate input gear portion 157 a thereof is disposedin meshed engagement with arcuate output gear portion 155 b oftransmission gear 154, and second intermediate gear 158 is positioneddistally adjacent transmission gear 154 such that arcuate input gearportion 159 a thereof is disposed in meshed engagement with arcuateoutput gear portion 155 b of transmission gear 154, although otherconfigurations are also contemplated. First and second intermediategears 156, 158 are rotatably mounted about pins 157 c, 159 c,respectively, that are fixed relative to and extend transversely throughbody portion 111 of housing 110.

Arcuate output gear portion 157 b of first intermediate gear 156 isconfigured to be disposed in meshed engagement with output gear 160,e.g., linear gear rack 134 of drive bar 130, during a first portion “S₁”of the full output stroke length “S_(f)” of drive bar 130. However, oncedrive bar 130 is moved distally along the full output stroke length“S_(f)” beyond the first portion “S₁” to a second portion “S₂” thereof,linear gear rack 134 is moved distally of and out of engagement witharcuate output gear portion 157 b of first intermediate gear 156.

Arcuate output gear portion 159 b of second intermediate gear 158 isconfigured to be disposed in meshed engagement with output gear 160,e.g., linear gear rack 134 of drive bar 130, during a second portion“S₂” of the full output stroke length “S_(f)” of drive bar 130. That is,once drive bar 130 is moved distally beyond the first portion “S₁” tothe second portion “S₂,” linear gear rack 134 is moved into engagementwith arcuate output gear portion 159 b of second intermediate gear 158.During the first portion “S₁,” linear gear rack 134 is disposedproximally of and out of engagement with arcuate output gear portion 159b of second intermediate gear 158.

In embodiments, the diameter of arcuate input gear portion 157 a offirst intermediate gear 156 is different than the diameter “D₁” ofarcuate output gear portion 157 b of first intermediate gear 158.Similarly, in embodiments, the diameter of arcuate input gear portion159 a of second intermediate gear 158 is different than the diameter“D₂” of arcuate output gear portion 159 b of second intermediate gear158. Further, the diameters of arcuate input gear portions 157 a, 159 amay be similar, in embodiments. The diameters “D₁” and “D₂” of arcuateoutput gear portions 157 b, 159 b, respectively, in embodiments, may bedifferent, as detailed below.

With continued reference to FIGS. 1, 2, 5, and 6, and to FIGS. 5 and 6in particular, as a result of the above-detailed configuration, pivotingof trigger 122 from the un-actuated position towards the actuatedposition rotates input gear 152 in a counter-clockwise direction (asviewed from the orientation shown in FIGS. 5 and 6). Counter-clockwiserotation of input gear 152, in turn, rotates transmission gear 154 in aclockwise direction (as viewed from the orientation shown in FIGS. 5 and6), due to the meshed engagement between arcuate gear portion 128 ofinput gear 152 and arcuate input gear portion 155 a of transmission gear154. Clockwise rotation of transmission gear 154 rotates both first andsecond intermediate gears 156, 158 in a counter-clockwise direction (asviewed from the orientation shown in FIGS. 5 and 6), due to the meshedengagement between arcuate output gear portion 155 b of transmissiongear 154 and arcuate input gear portions 157 a, 159 a of first andsecond intermediate gears 156, 158, respectively.

During the first portion “S₁” of the full output stroke length “S_(f)”of drive bar 130, wherein arcuate output gear portion 157 b of firstintermediate gear 156 is disposed in meshed engagement with linear gearrack 134 of drive bar 130, the counter-clockwise rotation of firstintermediate gear 156 translates drive bar 130 distally through bodyportion 111 of housing 110, while the counter-clockwise rotation ofsecond intermediate gear 158 has no effect.

During the second portion “S₂” of the full output stroke length “S_(f)”of drive bar 130, wherein arcuate output gear portion 159 b of secondintermediate gear 158 is disposed in meshed engagement with linear gearrack 134 of drive bar 130, the counter-clockwise rotation of secondintermediate gear 158 translates drive bar 130 distally through bodyportion 111 of housing 110, while the counter-clockwise rotation offirst intermediate gear 156 has no effect.

The above-detailed distal advancement of drive bar 130, in response toactuation of trigger 122, occurs against the biasing of biasing member140. As such, upon release of trigger 122, the bias of biasing member140 pulls drive bar 130 proximally, thereby urging second intermediategear 158 to rotate clockwise (as viewed from the orientation shown inFIGS. 5 and 6) during the second portion “S₂” of the full output strokelength “S_(f)” of drive bar 130 and urging first intermediate gear 156to rotate clockwise (as viewed from the orientation shown in FIGS. 5 and6) during the first portion “S₁” of the full output stroke length“S_(f)” of drive bar 130. The rotations of second and first intermediategears 158, 156 each, in turn, rotates transmission gear 154counter-clockwise (as viewed from the orientation shown in FIGS. 5 and6) and, thus, first gear 152 clockwise (as viewed from the orientationshown in FIGS. 5 and 6), thereby returning trigger 122 towards theun-actuated position.

The above-detailed actuation mechanism 120 provides a compactconfiguration to enable use with reposable surgical clip applier 10(FIGS. 1-2), wherein elongated assemblies, e.g., elongated assemblies200, 300 (FIGS. 3 and 4), are releasably engagable with handle assembly100 of reposable surgical clip applier 10 (FIGS. 1-2); however,actuation mechanism 120 is equally applicable for use with integratedsurgical clip appliers and other configurations of surgical clipappliers.

The above-detailed actuation mechanism 120 is configured, as notedabove, such that diameter “D₁” of arcuate output gear portion 157 b offirst intermediate gear 156 is different from diameter “D₂” of thearcuate output gear portion 159 b of second intermediate gear 158. Assuch, a different mechanical advantage is provided during the firstportion “S₁” of the full output stroke length “S_(f)” of drive bar 130(and, thus, a corresponding first portion “α₁” of an input rotation“α_(f)” of trigger 122) as compared to the second portion “S₂” thereof(and, thus, a corresponding second portion “α₂” of the input rotation“α_(f)” of trigger 122). In embodiments, diameter “D₁” is greater thandiameter “D₂” and the mechanical advantage during the first portion “S₁”is less than the mechanical advantage during the second portion “S₂.”Such a configuration is advantageous at least because the greatermechanical advantage is provided during the second portion “S₂,” wherejaws of the end effector assembly of the elongated assembly are urged toa closed position relative to one another to fire the surgical clip,which requires greater force as compared to the first portion “S₁,”where the surgical clip is loaded into the jaws. However, otherconfigurations are also contemplated, depending upon the particularconfiguration of the elongated assembly utilized and the mechanicaladvantages sought.

In embodiments, the mechanical advantage provided during the firstportion “S₁” of the full output stroke length “S_(f)” is 0.6 to 1.0, inembodiments, 0.7 to 0.9 and, in embodiments, about 0.8 (wherein the“about” takes into account manufacturing, material, environmental, andother tolerances). In embodiments, the mechanical advantage providedduring the second portion “S₂” of the full output stroke length “S_(f)”is 3.5 to 4.0, in embodiments, 3.6 to 3.9 and, in embodiments, about3.75 (wherein the “about” takes into account manufacturing, material,environmental, and other tolerances). In embodiments, the averagemechanical advantage over the full output stroke length “S_(f)” is 1.65to 1.8, in embodiments, 1.70 to 1.75, and, in embodiments, about 1.73(wherein the “about” takes into account manufacturing, material,environmental, and other tolerances). In embodiments, the ratio of themechanical advantage over second portion “S₂” of the full output strokelength “S_(f)” to the mechanical advantage over the first portion “S₁”of the full output stroke length “S_(f)” is 3 to 6, in embodiments, 4 to5, and, in embodiments, 4.25 to 4.75.

The first and second portions “S₁” and “S₂” of the full output strokelength “S_(f)” may be equal, e.g., each corresponding to ½ of the fulloutput stroke length “Se,” or may be different. In embodiments, thefirst portion “S₁” defines ½ to ¾ of the full output stroke length“S_(f)” and, in embodiments, about ⅔ of the full output stroke length“S_(f)” (wherein the “about” takes into account manufacturing, material,environmental, and other tolerances). In embodiments, the second portion“S₂” defines ¼ to ½ of the full output stroke length “S_(f)” and, inembodiments, about ⅓ of the full output stroke length “S_(f)” (whereinthe “about” takes into account manufacturing, material, environmental,and other tolerances).

In embodiments, the full output stroke length “S_(f)” is 1.0 inch to 1.4inches, in embodiments, 1.1 inches to 1.3 inches, and, in embodiments,about 1.2 inches (wherein the “about” takes into account manufacturing,material, environmental, and other tolerances). In embodiments, thefirst portion “S₁” is 0.6 inches to 1.0 inch, in embodiments, 0.7 inchesto 0.9 inches, and, in embodiments, about 0.8 inches (wherein the“about” takes into account manufacturing, material, environmental, andother tolerances). In embodiments, the second portion “S₂” is 0.2 inchesto 0.6 inches, in embodiments, 0.3 inches to 0.5 inches, and, inembodiments, about 0.4 inches (wherein the “about” takes into accountmanufacturing, material, environmental, and other tolerances).

In embodiments, the full input rotation “α_(f)” of trigger 122 is 35 to45 degrees, in embodiments, 37.5 degrees to 42.5 degrees, and, inembodiments, about 40 degrees (wherein the “about” takes into accountmanufacturing, material, environmental, and other tolerances). The firstand second portions “α₁” and “α₂” of the full input rotation “α_(f)” oftrigger 122 may be equal, e.g., each corresponding to ½ of the fullinput rotation “α_(f),” or may be different. In embodiments, the firstportion “α₁” defines ¼ to ½ of the full input rotation “α_(f)” and, inembodiments, about ⅓ of the full input rotation “α_(f)” (wherein the“about” takes into account manufacturing, material, environmental, andother tolerances). In embodiments, the second portion “α₂” defines ½ to¾ of the full input rotation “α_(f)″” and, in embodiments, about ⅔ ofthe full input rotation “α_(f)” (wherein the “about” takes into accountmanufacturing, material, environmental, and other tolerances).

In embodiments, the first portion “α₁” of the full input rotation“α_(f)” is 7.5 degrees to 17.5 degrees, in embodiments, 10 degrees to 15degrees, and, in embodiments, about 12.5 degrees (wherein the “about”takes into account manufacturing, material, environmental, and othertolerances). In embodiments, the second portion “α₂” of the full inputrotation “α_(f)” is 22.5 degrees to 32.5 degrees, in embodiments, 25degrees to 30 degrees, and, in embodiments, about 27.5 degrees (whereinthe “about” takes into account manufacturing, material, environmental,and other tolerances).

The relative diameters of arcuate gear portion 128, arcuate input gearportion 155 a, arcuate output gear portion 155 b, arcuate input gearportion 157 a, arcuate output gear portion 157 b, arcuate input gearportion 159 a, and arcuate output gear portion 159 b are selected so asto achieve the desired first and second mechanical advantages, ratiotherebetween, input rotations, and/or output stroke lengths, as detailedabove.

It should be understood that the foregoing description is onlyillustrative of the present disclosure. Various alternatives andmodifications can be devised by those skilled in the art withoutdeparting from the disclosure. Accordingly, the present disclosure isintended to embrace all such alternatives, modifications and variances.The embodiments described with reference to the attached drawing figuresare presented only to demonstrate certain examples of the disclosure.Other elements, steps, methods and techniques that are insubstantiallydifferent from those described above and/or in the appended claims arealso intended to be within the scope of the disclosure.

What is claimed is:
 1. An actuation mechanism for a surgical clipapplier, the actuation mechanism comprising: a drive bar movable througha stroke having a stroke length comprising a first portion and a secondportion to fire at least one surgical clip, the drive bar including anoutput gear rack associated therewith; a trigger pivotable from anun-actuated position to an actuated position; a first intermediate gearincluding an input portion and an output portion, the input portionoperably coupled to the trigger such that pivoting of the trigger fromthe un-actuated position to the actuated position rotates the firstintermediate gear; and a second intermediate gear including an inputportion and an output portion, the output portions of the first andsecond intermediate gears defining different diameters, the inputportion of the second intermediate gear operably coupled to the triggersuch that pivoting of the trigger from the un-actuated position to theactuated position rotates the second intermediate gear, wherein, in thefirst portion of the stroke length, the output portion of the firstintermediate gear is disposed in direct meshed engagement with the gearrack and the output portion of the second intermediate gear isdisengaged from the gear rack such that the first intermediate geardrives the drive bar along the first portion of the stroke length inresponse to pivoting of the trigger, wherein, in the second portion ofthe stroke length, the output portion of the second intermediate gear isdisposed in direct meshed engagement with the gear rack and the outputportion of the first intermediate gear is disengaged from the gear racksuch that the second intermediate gear drives the drive bar along thesecond portion of the stroke length in response to pivoting of thetrigger, and wherein a different mechanical advantage is provided in thefirst portion of the stroke length as compared to the second portion ofthe stroke length.
 2. The actuation mechanism according to claim 1,wherein the mechanical advantage provided in the first portion of thestroke length is less than the mechanical advantage provided in thesecond portion of the stroke length.
 3. The actuation mechanismaccording to claim 1, wherein the first portion of the stroke length isgreater than the second portion of the stroke length.
 4. The actuationmechanism according to claim 1, wherein the trigger is pivotable throughan input rotation from the un-actuated position to the actuatedposition, the input rotation including a first portion corresponding tothe first portion of the stroke length and a second portioncorresponding to the second portion of the stroke length.
 5. Theactuation mechanism according to claim 4, wherein the first portion ofthe input rotation is less than the second portion of the inputrotation.
 6. The actuation mechanism according to claim 5, wherein thefirst portion of the stroke length is greater than the second portion ofthe stroke length.
 7. The actuation mechanism according to claim 1,further comprising: an input gear associated with the trigger; and atransmission gear including an input portion and an output portion, theinput portion of the transmission gear disposed in meshed engagementwith the input gear and the output portion of the transmission geardisposed in meshed engagement with the input portions of the first andsecond intermediate gears.
 8. A handle assembly of a surgical clipapplier, comprising: a housing defining a body portion and a fixedhandle portion extending from the body portion; a drive bar slidablysupported within the body portion of the housing and movable relativethereto through a stroke having a stroke length comprising a firstportion and a second portion to fire at least one surgical clip, thedrive bar including an output gear rack associated therewith; a triggerpivotably connected to the housing and movable relative to the fixedhandle portion thereof from an un-actuated position to an actuatedposition; a first intermediate gear including an input portion and anoutput portion, the input portion operably coupled to the trigger suchthat pivoting of the trigger from the un-actuated position to theactuated position rotates the first intermediate gear; and a secondintermediate gear including an input portion and an output portion, theoutput portions of the first and second intermediate gears definingdifferent diameters, the input portion of the second intermediate gearoperably coupled to the trigger such that pivoting of the trigger fromthe un-actuated position to the actuated position rotates the secondintermediate gear, wherein, in the first portion of the stroke length,the output portion of the first intermediate gear is disposed in directmeshed engagement with the gear rack and the output portion of thesecond intermediate gear is disengaged from the gear rack such that thefirst intermediate gear drives the drive bar along the first portion ofthe stroke length in response to pivoting of the trigger, wherein, inthe second portion of the stroke length, the output portion of thesecond intermediate gear is disposed in direct meshed engagement withthe gear rack and the output portion of the first intermediate gear isdisengaged from the gear rack such that the second intermediate geardrives the drive bar along the second portion of the stroke length inresponse to pivoting of the trigger, and wherein a different mechanicaladvantage is provided in the first portion of the stroke length ascompared to the second portion of the stroke length.
 9. The handleassembly according to claim 8, wherein the mechanical advantage providedin the first portion of the stroke length is less than the mechanicaladvantage provided in the second portion of the stroke length.
 10. Thehandle assembly according to claim 8, wherein the first portion of thestroke length is greater than the second portion of the stroke length.11. The handle assembly according to claim 8, wherein the trigger ispivotable through an input rotation from the un-actuated position to theactuated position, the input rotation including a first portioncorresponding to the first portion of the stroke length and a secondportion corresponding to the second portion of the stroke length,wherein the first portion of the input rotation is less than the secondportion of the input rotation, and the first portion of the strokelength is greater than the second portion of the stroke length.
 12. Thehandle assembly according to claim 8, further comprising: an input gearassociated with the trigger; and a transmission gear including an inputportion and an output portion, the input portion of the transmissiongear disposed in meshed engagement with the input gear and the outputportion of the transmission gear disposed in meshed engagement with theinput portions of the first and second intermediate gears.
 13. Thehandle assembly according to claim 8, wherein the housing is configuredto receive an elongated assembly supporting an end effector assembly ata distal end portion thereof, and wherein the drive bar is configured tooperably interface with an actuation member of the elongated assembly.14. A surgical clip applier, comprising: a handle assembly; and anelongated assembly extending distally from the handle assembly andsupporting an end effector assembly at a distal end portion thereof,elongated assembly including an actuation member movable to fire atleast one surgical clip from the end effector assembly, wherein thehandle assembly includes: a housing defining a body portion and a fixedhandle portion extending from the body portion; a drive bar slidablysupported within the body portion of the housing and movable relativethereto through a stroke having a stroke length comprising a firstportion and a second portion to fire at least one surgical clip, thedrive bar including an output gear rack associated therewith; a triggerpivotably connected to the housing and movable relative to the fixedhandle portion thereof from an un-actuated position to an actuatedposition; a first intermediate gear including an input portion and anoutput portion, the input portion operably coupled to the trigger suchthat pivoting of the trigger from the un-actuated position to theactuated position rotates the first intermediate gear; and a secondintermediate gear including an input portion and an output portion, theoutput portions of the first and second intermediate gears definingdifferent diameters, the input portion of the second intermediate gearoperably coupled to the trigger such that pivoting of the trigger fromthe un-actuated position to the actuated position rotates the secondintermediate gear, wherein, in the first portion of the stroke length,the output portion of the first intermediate gear is disposed in directmeshed engagement with the gear rack and the output portion of thesecond intermediate gear is disengaged from the gear rack such that thefirst intermediate gear drives the drive bar along the first portion ofthe stroke length in response to pivoting of the trigger, wherein, inthe second portion of the stroke length, the output portion of thesecond intermediate gear is disposed in direct meshed engagement withthe gear rack and the output portion of the first intermediate gear isdisengaged from the gear rack such that the second intermediate geardrives the drive bar along the second portion of the stroke length inresponse to pivoting of the trigger, and wherein a different mechanicaladvantage is provided in the first portion of the stroke length ascompared to the second portion of the stroke length.
 15. The surgicalclip applier according to claim 14, wherein the mechanical advantageprovided in the first portion of the stroke length is less than themechanical advantage provided in the second portion of the strokelength.
 16. The surgical clip applier according to claim 14, wherein thefirst portion of the stroke length is greater than the second portion ofthe stroke length.
 17. The surgical clip applier according to claim 14,wherein the trigger is pivotable through an input rotation from theun-actuated position to the actuated position, the input rotationincluding a first portion corresponding to the first portion of thestroke length and a second portion corresponding to the second portionof the stroke length.
 18. The surgical clip applier according to claim17, wherein the first portion of the input rotation is less than thesecond portion of the input rotation, and the first portion of thestroke length is greater than the second portion of the stroke length.19. The surgical clip applier according to claim 14, further comprising:an input gear associated with the trigger; and a transmission gearincluding an input portion and an output portion, the input portion ofthe transmission gear disposed in meshed engagement with the input gearand the output portion of the transmission gear disposed in meshedengagement with the input portions of the first and second intermediategears.
 20. The surgical clip applier according to claim 14, wherein theelongated assembly is releasably engagable with the handle assembly.